The aim of this study was to investigate the effect of the addition of fungal solid-state fermented product (FP) enriched with gamma-linolenic acid (GLA) and β-carotene to feed on the haematological and immunological parameters of broiler chickens. Eighty 1-day-old COBB 500 broiler chickens were divided into two groups. The control group was fed with basic diets and chickens of the experimental group received 10% addition of FP, while the amount of basic diet was reduced. FP was produced during a solid-state fermentation (SSF) process using Umbellopsis isabellina CCF2412 as a producer of GLA and β-carotene. After 38 days of feeding, blood samples were collected and analyzed. Lower total and LDL-cholesterol values were measured in blood samples of the experimental animals (p<0.05). However, the triacylglycerol content was higher in the experimental group (p<0.05). Significantly higher levels of hematocrit and hemoglobin, and lower eosinophil and basophil content in the experimental group were recorded (p<0.05). The experimental group showed higher numbers of B lymphocytes and greater phagocytic capacity (p<0.05). The results indicate that a fermented product produced by SSF, using the fungal strain Umbellopsis isabellina, is a good source of GLA and β-carotene, which can influence the biochemical, hematological and immunological parameters of broiler chickens.